Abstract: Employing high-arsenic anthracite and employing a tubular furnace, the release of arsenic and the variation of arsenic speciation in ash under low-load coal combustion conditions was investigated. Results show that within the temperature range of 800-900 ℃, the release rate of arsenic from coal exhibits a significant peak with increasing temperature, while the proportion of As³⁺ in ash shows an upward trend. And the proportion of weak adsorbed arsenic in ash gradually increases within 800-900 ℃, which reaches its peak at 900 ℃. Within the range of 1 000-1 200 ℃, weak adsorbed arsenic in ash undergoes oxidation and decomposition, leading to an increase in the proportion of arsenate, prompting the transition of As³⁺ to As⁵⁺, and consequently, the proportion of As³⁺ decreases gradually. The increase of the volume fraction for O₂ facilitates the oxidation process of As³⁺ in ash. Furthermore, with the extension of coal particle residence time in the furnace, the release rate of arsenic from coal synchronously varies with the proportion of As³⁺ in ash.